CaffeineNCT07056231
Effect of Low-Dose Caffeine on Performance in Elite Sitting Volleyball Players
A study testing Caffeine in people with Caffeine and Physical Endurance, run by Ulaç Can YILDIRIM at 1 site in Turkey (Türkiye).
Trial summary
Background: Sitting volleyball is a sport that relies primarily on upper body strength and anaerobic capacity. In critical in-game skills such as serve and spike, factors such as speed-endurance time and impact power play a decisive role in performance. Read more about this study
- Who is it for?
- Ages 18 to 35 years, men only
- Conditions the study is for
- Caffeine, Physical Endurance, Muscle Strength
- What is being tested?
- Caffeine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 13 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 5 Mar 2025to 12 Mar 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- Men only
- No healthy volunteers
- Adult
Who may be able to join
- Male sitting volleyball players aged between 18 and 40
- Member of the 2024 National Sitting Volleyball Team
- At least 3 years of competitive playing experience
- No caffeine consumption 48 hours prior to testing
- Provided informed consent to participate
Who cannot join
- Known cardiovascular, neurological, or metabolic disorders
- Current use of medications that may affect caffeine metabolism
- Allergy or sensitivity to caffeine
- Use of performance-enhancing substances within the last month
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Karamanoğlu Mehmetbey University
Karaman, Central, 695002
About this study
Official title: The Effect of Low Dose Caffeine on Serve Speed, Spike Speed, and Speed-Endurance in Elite Sitting Volleyball Players: A Randomized Double-Blind Crossover Study
Background: Sitting volleyball is a sport that relies primarily on upper body strength and anaerobic capacity. In critical in-game skills such as serve and spike, factors such as speed-endurance time and impact power play a decisive role in performance. There are limited studies in the literature examining the effects of low-dose caffeine consumption on these skills. The effects of ergogenic supplements in Paralympic sports have not been sufficiently investigated, and the potential benefits of caffeine on serve and spike performance in sitting volleyball players remain unclear. Purpose: The main purpose of this research was to determine the effects of low-dose caffeine (3 mg/kg) consumption on the serve speed, spike speed and Speed-Endurance performances of elite-level sitting volleyball players. Method: The study was designed using a randomized, double-blind, balanced, and crossover experimental design. 13 elite male athletes from the 2024 Paravolley European Champion Sitting Volleyball Men's National Team participated in the study. Participants were evaluated for serve speed, spike speed, and speed-endurance performances in both 3 mg/kg caffeine (CAF) and placebo (PLA) conditions.
Read the detailed description
This study aimed to investigate the effects of low-dose caffeine ingestion on key performance parameters in elite-level sitting volleyball athletes. Sitting volleyball is a Paralympic sport that relies heavily on upper body explosive strength and short-term anaerobic power. While caffeine is a well-known ergogenic aid in able-bodied sports, its role in Paralympic contexts remains underexplored. Using a randomized, double-blind, placebo-controlled crossover design, the effects of 3 mg/kg caffeine consumption were assessed in 13 elite male sitting volleyball players. Each participant completed performance assessments under both caffeine and placebo conditions. The primary goal was to examine whether caffeine intake would enhance serve speed, spike speed, and repeated sprint ability. The study provides new insights into the acute ergogenic effects of caffeine in Paralympic team sport athletes, highlighting its selective benefit on explosive upper-body tasks such as serving.
- Conditions
- Caffeine, Physical Endurance, Muscle Strength, Paralympic Athletes
- Being tested
- Caffeine, Placebo
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CaffeineDietary supplement
A single oral dose of 3 mg of caffeine per kilogram of body weight form approximately 60 minutes before performance testing. Supplied by Oxford Vitality, ISO-certified.
PlaceboDietary supplement
polydextrose used as Placebo
| Study group | Role | What they receive |
|---|---|---|
| Low-Dose Caffeine Arm | Experimental | Participants receive a single oral dose of caffeine (3 mg/kg) during the first session and a placebo in the second session. There is a washout period of at least 48 hours between sessions. Receives: Dietary Supplement: Caffeine; Dietary Supplement: Placebo |
| Placebo Arm | Experimental | Participants receive a placebo during the first session and a single oral dose of caffeine (3 mg/kg) in the second session. There is a washout period of at least 48 hours between sessions. Receives: Dietary Supplement: Caffeine; Dietary Supplement: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Serve Speed
Serve speed will be assessed using a calibrated radar device to record peak velocity of each participant's volleyball serve.
Measured: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
Spike Speed
Maximum spike speed will be measured in kilometers per hour (km/h) using a radar gun during a standardized spike task conducted after supplementation in each condition.
Measured: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
Speed-Endurance
The number of maximal shuttle runs completed in a repeated sprint ability (RSA) test protocol will be recorded to assess speed-endurance capacity.
Measured: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jul 2025
- Study start5 Mar 2025
- Primary completion11 Mar 2025
- Study completion12 Mar 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for CaffeineStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 13 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ulaç Can YILDIRIM
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Ulaç Can YILDIRIM, Sinop University
- Investigators
- Ulas C Yildirim, Study chair, sinop university faculty of sport sciences
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07056231
- Sponsor's protocol ID
- 2025/91
- Status last verified
- Jun 2025
- First submitted
- 21 Jun 2025
- Last updated
- 9 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Diedhiou AB, Erkan D, Guler M, Sar H, Karakulak I, Eyuboglu E, Gundem MC, Karayigit R, Tuncer SY, Yildirim UC. The effect of low dose caffeine powder supplementation on serve speed, spike speed, and speed-endurance in elite sitting volleyball players: a randomized double-blind crossover study. BMC Sports Sci Med Rehabil. 2025 Nov 6;17(1):320. doi: 10.1186/s13102-025-01408-8.
PubMed 41199325
Study at a glance
From the registry record, last updated by the sponsor on 9 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Low Dose Caffeine on Serve Speed, Spike Speed, and Speed-Endurance in Elite Sitting Volleyball Players: A Randomized Double-Blind Crossover Study
- ClinicalTrials.gov ID
- NCT07056231
- Acronym / sponsor ID
- 2025/91
- Conditions
- Caffeine, Physical Endurance, Muscle Strength, Paralympic Athletes
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 13 participants (actual)
- Lead sponsor
- Ulaç Can YILDIRIMUniversity, hospital or other
- Study start
- 5 Mar 2025 (actual)
- Primary completion
- 11 Mar 2025 (actual)
- Study completion
- 12 Mar 2025 (actual)
- First posted
- 9 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Background: Sitting volleyball is a sport that relies primarily on upper body strength and anaerobic capacity. In critical in-game skills such as serve and spike, factors such as speed-endurance time and impact power play a decisive role in performance. There are limited studies in the literature examining the effects of low-dose caffeine consumption on these skills. The effects of ergogenic supplements in Paralympic sports have not been sufficiently investigated, and the potential benefits of caffeine on serve and spike performance in sitting volleyball players remain unclear. Purpose: The main purpose of this research was to determine the effects of low-dose caffeine (3 mg/kg) consumption on the serve speed, spike speed and Speed-Endurance performances of elite-level sitting volleyball players. Method: The study was designed using a randomized, double-blind, balanced, and crossover experimental design. 13 elite male athletes from the 2024 Paravolley European Champion Sitting Volleyball Men's National Team participated in the study. Participants were evaluated for serve speed, spike speed, and speed-endurance performances in both 3 mg/kg caffeine (CAF) and placebo (PLA) conditions.
Detailed description
This study aimed to investigate the effects of low-dose caffeine ingestion on key performance parameters in elite-level sitting volleyball athletes. Sitting volleyball is a Paralympic sport that relies heavily on upper body explosive strength and short-term anaerobic power. While caffeine is a well-known ergogenic aid in able-bodied sports, its role in Paralympic contexts remains underexplored. Using a randomized, double-blind, placebo-controlled crossover design, the effects of 3 mg/kg caffeine consumption were assessed in 13 elite male sitting volleyball players. Each participant completed performance assessments under both caffeine and placebo conditions. The primary goal was to examine whether caffeine intake would enhance serve speed, spike speed, and repeated sprint ability. The study provides new insights into the acute ergogenic effects of caffeine in Paralympic team sport athletes, highlighting its selective benefit on explosive upper-body tasks such as serving.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Low-Dose Caffeine Arm | Experimental | Dietary Supplement: Caffeine, Dietary Supplement: PlaceboParticipants receive a single oral dose of caffeine (3 mg/kg) during the first session and a placebo in the second session. There is a washout period of at least 48 hours between sessions. |
| Placebo Arm | Experimental | Dietary Supplement: Caffeine, Dietary Supplement: PlaceboParticipants receive a placebo during the first session and a single oral dose of caffeine (3 mg/kg) in the second session. There is a washout period of at least 48 hours between sessions. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Male sitting volleyball players aged between 18 and 40
- Member of the 2024 National Sitting Volleyball Team
- At least 3 years of competitive playing experience
- No caffeine consumption 48 hours prior to testing
- Provided informed consent to participate
Key exclusion criteria (4 listed)
- Known cardiovascular, neurological, or metabolic disorders
- Current use of medications that may affect caffeine metabolism
- Allergy or sensitivity to caffeine
- Use of performance-enhancing substances within the last month
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| CaffeineA single oral dose of 3 mg of caffeine per kilogram of body weight form approximately 60 minutes before performance testing. Supplied by Oxford Vitality, ISO-certified. | Dietary supplement | Low-Dose Caffeine Arm, Placebo Arm |
| Placebopolydextrose used as Placebo | Dietary supplement | Low-Dose Caffeine Arm, Placebo Arm |
Primary outcome
Serve Speed
Time frame: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
Serve speed will be assessed using a calibrated radar device to record peak velocity of each participant's volleyball serve.
Spike Speed
Time frame: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
Maximum spike speed will be measured in kilometers per hour (km/h) using a radar gun during a standardized spike task conducted after supplementation in each condition.
Speed-Endurance
Time frame: After 60 minutes ingestion of the supplement on test day (CAF and PLA)
The number of maximal shuttle runs completed in a repeated sprint ability (RSA) test protocol will be recorded to assess speed-endurance capacity.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jul 2025.
- Derived from this study: PubMed 41199325Diedhiou AB, Erkan D, Guler M, Sar H, Karakulak I, Eyuboglu E, Gundem MC, Karayigit R, Tuncer SY, Yildirim UC. The effect of low dose caffeine powder supplementation on serve speed, spike speed, and speed-endurance in elite sitting volleyball players: a randomized double-blind crossover study. BMC Sports Sci Med Rehabil. 2025 Nov 6;17(1):320. doi: 10.1186/s13102-025-01408-8.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Ulas C Yildirim study chair
sinop university faculty of sport sciences
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Caffeine in people with Caffeine and Physical Endurance, run by Ulaç Can YILDIRIM at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 9 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Serve Speed (time frame: After 60 minutes ingestion of the supplement on test day (CAF and PLA)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07056231, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jul 2025.